This invention relates to a method and apparatus for providing balanced stacks of diapers and, more particularly, to a method and apparatus for orienting a series of diapers where adjacent diapers are disposed 180 degrees to those adjacent.
The invention finds particular application to the packaging of disposable diapers. These diapers, like their historic cloth counterparts, are folded so as to develop a crotch which necessarily has greater thickness (by virtue of the fold) than the opposite free edge portions to be secured about the infant's waist. The concept of reversing products to develop balanced stacks is, of course, old. For example, the general idea was employed in coowned Spencer U.S. Pat. No. 4,015,724 relative to stacks of business forms.
In the handling of disposable diapers, however, the problems were different--because of handling a relatively bulky and extensive product at high speed. For example, contemporary diaper manufacturing machines produce approximately 300 units per minute. The time constraint of performing the necessary orientation in 1/5 second has not been adequately met by existing methods and apparatus. One currently employed expedient utilizes a pair of folding drums equipped with oscillating fingers to develop the 180 degrees alternate stacking. In other words, a first diaper was gripped by one drum and the crotch portion directed one way after which it was finger stripped and thereafter the next diaper was gripped by the adjacent drum with its crotch disposed the opposite way and that in turn stripped by a second finger means. This resulted in a method that was complicated and time-consuming and, more particularly, apparatus that was complicated and hence more subject to accelerated wear.
According to the invention, these problems have been solved through the use of a single drum interposed in the path of a stream of series of diapers from the diaper manufacturing machine and wherein the drum is equipped with vacuumized turning devices for sequentially turning the diapers alternates 90 degrees so as to develop the desired 180 degree orientation from adjacent diaper to adjacent diaper. Some of the mechanism employed is patterned after that disclosed in Wierzba and Spencer U.S. Pat. No. 3,728,191 which was employed for 90 degree turning of the tape-tabs employed to provide diaper fastenings. It was surprising, however, that such mechanism could be used to advantage in properly orienting the relatively ponderous diapers.
Other objects and advantages of the invention may be seen in the details of construction and operation set down in this specification.